Redis is a caching tool and HTTP session store that allows you to save cached data and session information from your website to an external location. This means that your website doesn't have to calculate everything every time; instead, it can retrieve the data from the cache and load the website much faster. The user sessions are in memory even if the application goes down. Redis is a fast caching tool because it uses memory first. It has several useful advantages:

• Everything is stored in one place, so you only have to flush one cache.
• It is faster than Memcache. This is noticeable when using the websites of large shops.
• Sessions are stored in memory and not in the database.
• The backend becomes faster.

Redis is not merely a cache, but is also a data structure store. It is basically a database and should be viewed conceptually as such. With regard to its operation and how it handles data, it has more in common with a NoSQL database.